Definitely go with selectable in the front.
I had aussie lockers (automatic like a detroit locker) in the front and rear of a truck and driving in 4x4 in snow was a little tricky. Any tight maneuvering in 4x4 was tricky really, and you could really feel the steering tighten up even if you were light on the throttle. I carried a spare axleshaft (cv joints) and gear oil all the time because I figured it was going to break something soon. In 2wd you couldn't tell it was there as no torque was applied. I found myself switching to 2wd more often to maneuver on tight trails or driving on tight streets in the snow.
Now I have an Eaton E-locker in the front of my F150 and like it so far. No extra stress in most situations (open diff when unlocked), no tight steering when disengaged, but full traction when I need it.
For the rear axle, it depends on your use and preferences.
Personally I hate driving an open rear diff with a passion, whether on dry pavement, wet pavement, snow, etc. So I have never opted for a selectable rear locker. There are a lot of situations that call for more traction than an open diff, but not fully locked.
Limited slip is great on the road, good on gravel, dirt, sand, light snow but when you REALLY need the traction it isn't going to be there for you. It is no fun to be stuck in 18-24" of snow, or have a rear tire off the ground and see that your limited slip is effectively useless. However a front locker will help make up for that some. A true-trac is the only limited slip I would spend the money on.
My favorite setup for the rear axle was the aussie locker. I'm running a rear Detroit locker now and it basically functions the same from the driver's perspective but it is not as smooth as the aussie. Yes it is going to chirp tires when you turn tight and you're heavy on the throttle. Yes it is going to allow you to kick the rear end around if you romp on it in the rain/snow/mud, but it is very predictable once you get use to it. In my opinion it is more predictable than a limited slip on slippery surfaces. You get a feel for it and know exactly what it takes to lock it. On the trail they are great as well. It unlocks when you are turning tight and maneuvering, but locks when you are getting into the throttle and need the traction. No need to bother flipping switches, running a compressor all the time, etc. Due to the harshness (and backlash) though, most people would not like them in a daily driver. For what it's worth, if Aussie offered a lunchbox locker for my rear axle I would swap it in to replace the detroit in a heartbeat because it was so much smoother.
